Hydraulic systems

ABSTRACT

IN A VEHICLE HAVING A PLURALITY OF WORK PERFORMING MEANS THAT ARE POWERED BY HYDRAULIC FLUID THE IMPROVEMENT CHARACTERIZED BY A PLURALITY OF INDIVIDUAL AND SEPARATELY OPERABLE HYDRAULIC SYSTEMS FOR OPERATING THE RESPECTIVE WORK PERFORMING MEANS, THE RESPECTIVE MOTORS AND PUMPS, PREFERABLY, BEING POSITIONED RELATIVELY CLOSELY ADJACENT THE WORK PERFORMING MEANS FOR WHICH THEY SUPPLY HYDRAULIC FLUID UNDER PRESSURE. ALSO DISCLOSED ARE (1) A TYPE OF CONTROL VALVE THAT IS OPERABLE TO START A MOTOR DRIVING A RESPECTIVE PUMP SIMULTANEOUSLY WITH DIRECTING THE HIGH PRESSURE HYDRAULIC FLUID OUTPUT OF THE PUMP TO OPERATE THE WORK PERFORMING MEANS, (2) OTHER SPECIFIC STRUCTURAL FEATURES, AND (3) ADVANTAGES.   D R A W I N G

March 13, 1973 L. AJMOLBY v 3,720,332

HYDRAULIC SYSTEMS Filed April 27, 1971 I 2 Sheets-Sheet 1 if MAINGENERATOR 15% l l l CONTROL /55 T T T VALVE CONTACTOR r759 /67 /645 26]53 [6' 5. 9 n f] 125 147 49 g MAIN QONTROL PUMP MOTOR VALVE 1 59""//Vl/E/V7'0R /wydfiWa/y I B) m ATTORNEYS March 13, 1973 1.. A. MOLBY 2 3HYDRAULIC SYSTEMS Filed April 27, 1971 ZSheets-Sheet 2 United StatesPatent O 3,720,332 HYDRAULIC SYSTEMS Lloyd A. Molhy, Longview, Tern,assignor to R. G. Le Tourneau Inc., Longview, Tex. Filed Apr. 27, 1971,Ser. No. 137,881

Int. Cl. B66f 9/00 US. Cl. 214-140 14 Claims ABSTRACT OF THE DISCLOSUREIna vehicle having a plurality of work performing means that are poweredby hydraulic fluid the improvement characterized by a plurality ofindividual and separately operable hydraulic systems for operating therespective work performing means; the respective motors and pumps,preferably, being positioned relatively closely adjacent the workperforming means for which they supply hydraulic fluid under pressure.Also disclosed are (l) a type of control valve that is operable to starta motor driving a respective pump simultaneously with directing the highpressure hydraulic fluid output of the pump to operate the workperforming means; (2) other specific structural features; and (3)advantages.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to an improved hydraulic system for a vehicle having a pluralityof work performing means that are powered by hydraulic fluid. Moreparticularly, this invention relates to a plurality of separate andindividual hydraulic systems for operating and powering respective onesof the plurality of work performing means on the vehicle.

(2) Description of the prior art The prior art has seen a wide varietyof machines wherein a work function is performed by a hydraulicallypowered device. For example, in front end loaders or road grader typeequipment there are a large number of work functions that are performedby hydraulic means. Respective ones of the work functions may involve ahydraulic ram which is attached to a work piece. The hydraulic ram isused to raise and lower a bucket or grader blade, and to obtain thedesired degree of tilt and the respective positions thereof. It is thusapparent that numerous hydraulic rams, or cylinder-piston units, arerequired for each vehicle. It is also apparent that these hydraulic ramsare disbursed and disposed at various locations on the vehicle.

It is conventional practice in a machine of the type above-mentioned tohave a single hydraulic fluid reservoir and a single hydraulic pump forthe entire machine. The hydraulic pump is normally driven directly by atransmission means that is powered by the vehicles internal combustionengine. The hydraulic pump is run continuously while the machine isrunning. Thus, hydraulic flow is constantly available to a manifold andselected valves on the manifold permit the hydraulic fluid to flow toselected hydraulic rams.

Vehicles such as those described hereinbefore are subject to severaldisadvantages. First, there are long runs of tubing, connections andpivot connections from the single pump location to the various hydraulicram locations. Thismakes for a system that is expensive to install,diflicult to maintain and that requires care in operation to preventsevering one or more of the high pressure hoses in the cumbersome setup.Second, the single hydraulic pump must be running all the time that themachine is travelling and is generating maximum hydraulic flow 3,720,332Patented Mar. 13, 1973 whether or not such flow is being used. Thus,even when the machine is merely travelling on roads to and from itsdestination, the maximum hydraulic fluid flow is still maintained. Theexcess horsepower that is employed in circulating the fluid isdissipated as waste heat and requires additional cooling. Third, in theevent of failure of a hydraulic element such as the pump, the vehiclehas had to be shut down to effect repairs in the field, instead of beingable to drive the machine back to a central repaiar location whererepair is facilitated and more satisfactorily carried out.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view ofan articulated front end loader vehicle employing one embodiment of thisinvention.

FIG. 2 is a schematic isometric view of an embodiment of this inventionemploying a plurality of separate hydraulic systems.

FIG. 3 is a schematic diagram of a control valve employed in one controlmeans in a system in accordance with an embodiment of this invention.

FIG. 4 is a partial top plan view, partly schematic, illustrating anembodiment of this invention employing individual pumps and reservoirsin the hydraulic steering system.

FIG. 5 is a partial top plan view, partly schematic, illustrating anembodiment of this invention employing a separate hydraulic controlsystem for the hydraulic rams raising the main beams.

FIG. 6 is a partial plan view, partly schematic, illustrating ahydraulic system for controlling the tilt of the bucket.

DESCRIPTION OF PREFERRED EMBODIMENTS It is a primary object of thisinvention to provide an improvement in hydraulically operable powersystems for vehicles wherein hydraulic power is employed to operate aplurality of work performing means; the improved bydraulic systemobviating the disadvantages of the prior art type vehicles.

Other objects of this invention will be apparent to those familiar with'the art when the following description is read in conjunction with thedrawings.

Referring to FIG. 1, the present invention is shown incorporated in anarticulated front end loader type vehicle 11 having a front section 13and a rear section 15. The front section 13 has a pair of front wheels17. The rear section 15 has a pair of rear wheels 19. The front and rearsections 13 and 15 are pivotally connected via pivot connection 21 forhorizontal steering movement relative to one another about asubstantially vertical steering axis 23. Specifically, a hydraulic ram,comprising a cylinder, piston and shaft arrangement, is connected to thefront and rear sections on one or both sides of the pivot connection andeffects the desired degree of steering via a steering connection 25 inresponse to the steering means in the operators console. The steeringconnection 25 is disposed laterally from the pivot connection 21 for adesired moment arm over which the steering force can be applied. Asteering system such as described in my copending application Ser. No.137,936, entitled Two Speed Steering System, filed Apr. 27, 1971,provides an improved steering system for the articulated vehicle 11. Thehydraulic system, with its plurality of pumps for supplying hydraulicfluid under pressure will be described in more detail with regard toFIG. 4 hereinafter. It should be borne in mind, however, that thehydraulic steering system is one of the plurality of work performingmeans on the vehicle 11 that are powered by hydraulic fluid.

The vehicle 11 also carries hydraulic pumps 27 and 29 disposed closelyadjacent to the hydraulic rams 31 and 33 for which they supply hydraulicfluid at an elevated pressure. Disposed closely adjacent and connectedwith the respective pumps 27 and 29 are motors 35 and 37, as well as thecontrol valves and the reservoir (not shown in FIG. 1).

For clarity in explanation and understanding, a simple schematicisometric is illustrated in FIG. 2 showing the operation of thehydraulic rams raising and lowering the arms carrying the bucket and thehydraulic rams controlling the angle of tilt by way of the bell cranklinkage arrangement. Referring to FIG. 2, the bucket 41 is carried onmain beams, or arms, 43 that are pivotally mounted by way of a suitablepivot shaft 45 on the vehicle (not shown in FIG. 2). The main beams 43are cutaway to show the hydraulic rams 33 for raising and lowering themain beams in response to high pressure hydraulic fluid suitablydirected to either the piston end or the shaft end, respectively.Specifically, the hydraulic rams 33 are pivotally mounted by stub shaft47 connecting one end with the vehicle and a second stub shaft 49connecting the other end with the main beam 43. The hydraulic cylinderportion of the hydraulic ram 33 is connected at its piston end viaconduit 51 with a main control valve 53. Similarly, the shaft end of thecylinder portion of the hydraulic ram 33 is connected via conduit 55with the other side of the main control valve 53. The main control valve53 may be operably positioned to route hydraulic fluid at elevatedpressure into either conduit 51 for raising the main beam 43 or intoconduit 5,5 for power lowering of the main beam 43. If desired, ofcourse, the hydraulic fluid from the piston end may be routed back to ahydraulic reservoir and allow gravity to effect lowering of the bucket.Power lowering is advantageous, however, where tamping or the like isdesired. The main control valve 53 is connected with a first pump 57 byway of conduit 59 and with a reservoir, or sump, 61 by way of suitablefilter 63. The pump 57 is driven by a motor 65. The pump 57 is alsoconnected with the sump 61 via a filter 67 and conduit 69. The pump 57may be the same a pump 27.

The main control valve is hydraulically connected with a control valve71 by way of conduit such as conduits 73-76. The control valve 71 isoperably positioned by a suitable lever 79' and effects fluidpositioning of the main control valve so as to direct the main stream ofhigh pressure hydraulic fluid to the respective conduit 51 or 55.

The bucket 41 is tilted by movement of the bell crank 81 about itsfulcrum shaft 83. Specifically, the hydraulic rams 31 are pivotallyconnected at their one end with the vehicle via suitable shafts 85 andat their other end with the bell crank via shafts 87. The bottom end ofthe bell crank is connected with the bucket via link 89, FIG. 1, so'asto effect tilting of the bucket in response to lengthening or shorteningof the hydraulic ram 31. The cylinder portion of the hydraulic rams 31has their piston ends connected with the main control valve 95 viaconduit 91. Similarly, the cylinder portion of the hydraulic rams 31have their shaft ends connected with the main control valve 95 viaconduit 93.

The main control valve 95 is connected with a second hydraulic pump 97via conduit 99 and with the sump 61 via suitable conduit and filtermeans such as filters 63 and 101. The pump 97 is powered by a motor 103and is connected to the sump 61 via conduit 105, and filter 107. Themain control valve 95 is fluidly connected with control valve 109 viaconduits 111-114.

As illustrated, the main control valves 53 and 95 have a common housingand a common return conduit, as well as a common sump 61. Similarly, thepumps 5,7 and 97 have a common sump 61. The common sump may be employed,since the low pressure suction conduits 69 and 105 are not as easilydamaged as the high pressure conduits and can run from the common sumpto the pumps. Ad vantages, however, individual sumps, or reservoirs, areemployed and are disposed closely adjacent the pumps, as

4 will become apparent from FIGS. 4-6, which are described laterhereinafter.

As illustrated in FIG. 2, the control levers 79 and 117 a are positionedclosely adjacent each other to facilitate control of the height and theangle of tilt of the bucket by the operator. Such closely adjacentpositioning is not so much a requisite when a linkage arrangement suchas described in my co-pending patent application Ser. No. 835,464,entitled Front End Loader Type Vehicle, filed June 23, 1969 now Pat. No.3,606,061, granted Sept. 20, 1971; since, as described therein, thefront end loader has a self levelling feature in which the bucket isemplaced at its surface position with its bottom edge substantiallyhorizontal from its top position with the bottom edge being at the fulldump angle.

In operation, hydraulic fluid is supplied under pressure to the maincontrol valves '53 and via respective conduits 59 and 99. For example,the pumps 57 and 97 may have an output of about gallons per minute,respectively. The main control valves 53 and 95 divert a small portionthereof; for example, about 26 gallons per minute; to the control valves71 and 109'. The respective control valves 711 and 109, responsive tothe position of the control levers 79' and 117, route a required amountof high pressure fluid back to the main control valves 53 and 95 tosuitably position them, diverting the remainder of the hydraulic fluidback through the return position of the main control valves into sump61. For example, initially the bucket 41 may have its bottom edgelevelled by extension of the hydraulic ram 31. In such an event, themain control valve 95 is positioned to route high pressure hydraulicfluid via conduit 91 to the piston ends of the hydraulic rams 31,extending the respective shafts and effecting the desired levelling ofthe bottom of the bucket 41. Low pressure fluid from the shaft ends ofthe hydraulic rams 31 is returned through conduit 93 and through the lowpressure fluid passageway of the main control valve 95 to the sump 61.Once a desired load is obtained in the bucket 41, the lever 1 17 isoperated in the reverse direction to effect retraction of the hydraulicrams 31 and the desired tilt back of the bucket 41 to carry the load toits top position with minimal spilling. The lever 79 is operated toraise the bucket to its top position for dumping the load into asuitable receptacle such as a dump truck or the like. A portion of thediverted high pressure fluid is sent to position the main control valve53 to direct high pressure hydraulic fluid into conduit '51 and thenceinto the piston ends of the hydraulic rams 33. Consequently, the bucketends of the main beams 43 are raised about their pivot shafts 45 toeffect the desired height of the bucket 41. At this point, the controllever 117 is operated to dump the bucket 41. Specifically, the lever 117positions the control valve and ultimately effects a positioning of themain control valve 95 to direct high pressure hydraulic fluid intoconduit 93 to retract the shaft and move the bucket 41 into its dumpposition. Thereafter, the control lever 79 is positioned in thedirection opposite to which it was initially positioned to route highpressure hydraulic fluid into the conduit 55 and effect controlled,powered lowering of the bucket 41. As indicated hereinbefore, the lowpressure hydraulic fluid from the hydraulic rams is vented through therespective return conduits to the sump 61.

Advantageously, the motors 65 and 103 are not operating during the roadtravel of the vehicle 11 when the bucket 41 is moved to its road travelposition, such as its upper position where there is a minimum ofobstruction to visibility. Obviously, the motors 65 and 103 may becontrolled by a manual switch such as switch 119', FIG. 3. Such a manualswitch may be preferred for long periods of use and nonuse. It isfrequently advantageous to employ a switch means that is operativelyassociated with the control valve and its control lever to effectstarting and stopping of the motor synchronously with direction of thehydraulic fluid through the control valve via the main control valve toits desired operation of the work performing means. Referring to FIG. 3,the control valve 123 and the main control valve 125 serve as a controlmeans for controlling the work performing means such as one of the setsof hydraulic rams. The control valve 123 includes a plunger 127 that hasa groove means 129 disposed peripherally therearound. On each side ofthe groove means 129 are disposed cam means 131. The plunger 127 isconnected with a control lever 133. Any of the levers, linear ornon-linear, that are available on the market may be employed as thecontrol lever 133. Specifically, the control lever 133 is pivotallymounted for movement about a fulcrum shaft 135 and has its lower endconnected with the plunger 127 via link 137. Accordingly, the plunger[127 is moved inwardly or outwardly in response to the appropriatedirection of movement of the control lever 133. The control valve 123 isconnected via conduit 13 9 with the main control valve 125, as a sourceof high pressure hydraulic fluid diverted by the main control valve. Thecontrol valve 123 is also connected with the main control valve viasuitable conduit such as conduit 1 41 for effecting a respectiveposition of the main control valve and thereby effecting the desiredflow of high pressure hydraulic fluid to the work performing means. Themain control valve may be biased toward neutral, but moved in a givendirection against the biasing means by balanced hydraulic pressure orflow. The main control valve is conventional and need not be describedin detail herein.

The control valve 123 also has a bypass conduit 143 for bypassing anyunused high pressure fluid supplied by conduit 139. The bypass conduit143 may be returned to the main control valve 125 through appropriateconduit or directly to a reservoir 145.

The main control valve 125 is connected with the discharge of pump 147via conduit 149. The suction side of the pump 147 is connected with thereservoir 1 45 via conduit 151.

The pump 14'] is powered by motor 153. As illustrated, the motor 153 isa three-phase motor that is connected with the main generator 155 viacontactor 157 and associated conductors such as conductor 159. Thecontactor 157 is operable to effect series connection of the motor 153with the main generator 155 to energize the motor and start the pump 147in response to closure of a control switch associated with the contactor157. The control switch may be a manual switch 119, referencedhereinbefore, or it may be a switch such as switch 161 that is closed bymovement of the plunger 127. As illustrated, the switch 161 has a switchplunger 163 that is depressed by a pivotally mounted lever 165 to effecta closed switch. The lever 165 has a roller 167 carried at its free endand engaging the recess means 129. Consequently, as the plunger 127 ismoved inwardly or outwardly, the roller 16'7 cams up the cam means 131contiguous the recess means 129 to close the switch and energize themotor 153 via the contactor 157. The switches 1-61 and 119 are connectedin parallel and one or both may be employed as desired.

In operation, the operator of the vehicle will move control lever 133 ina predetermined direction to move the plunger 127 inwardly or outwardly.This movement closes the switch 161 and energizes the motor 153,starting pump 147. Hydraulic fluid is supplied to the main control valve125 which diverts a small portion to the control valve 123. A portion ofthe high pressure hydraulic fluid is returned, the amount beingproportional to movement of the plunger 127, through conduit 141 toefliect positioning of the main control valve 125. The remainder isbypassed to the reservoir, directly or indirectly, through conduit 143.The main control valve 125 effects the requisite flow of high pressurehydraulic fluid to the work performing means until the desired work isdone; for example, the main beam 43 is elevated to the desired height.Thereafter, the control lever 133 is released and is returned via aspring (not shown) to its shut-off position, opening switch 161 6through movement of the roller 167 into the recess means 129, andstopping pump 147. A liquid block is held on the work performing meansthrough the appropriate positioning of the main control valve 125.

Movement of the control lever 133 in the opposite direction again camsthe roller 167 up the opposite face of the cam means 131 contiguous therecess means 129 and starts the pump 147 as described hereinbefore. Thecontrol valve 123, however, positions the main control valve in theopposite direction; for example, by way of another conduit 169. In anyevent, the main control valve is positioned to effect a lowering of themain beam 43 and return of hydraulic fluid to the reservoir 145. Oncethe desired position, such as the surface position, of the bucket hasbeen achieved, the control lever 133 is released and automaticallyreturned to the shut-off position, stopping the pump and repositioningthe control valve and the main control valve, as described hereinbefore.While additional reference numerals have been given the elements in FIG.3, it is apparent that many of the elements are equivalent to recitedelements in FIG. 2. For example, the pump 147 may be the same as pump57, the control valve 123 may be employed as control valve 71 and themain control valve may be employed as the main control valve 53.

In FIGS. 4-6, discrete hydraulic systems are illustrated schematicallywith other systems cutaway for clarity of illustration.

Referring to FIG. 4, the steering system illustrated therein isdescribed in detail in my co-pending application Ser. No. 137,936,referenced hereinbefore. The steering system need not be described indetail since the hereinbefore referenced application Ser. No. 137,936can be referred to for such detailed explanation. A schematicoperational description will serve to illustrate the use of a pluralityof independently and separately operable hy draulic pumps to supplypower for the respective elements. Specifically, steering wheel 171operatively turns gerotor 173 to direct high pressure hydraulic fluidthrough one of the conduits 175 or 177 for effecting a predeterminedlength L of hydraulic ram interconnection means 179. The gerotor 173 issupplied hydraulic fluid at elevated pressure from pump 181 via conduit183. The pump 181 obtains its hydraulic fluid from reservoir 185. Thegerotor 173 routes low pressure hydraulic fluid back to the reservoir185 via conduit 187. Ordinarily, the pump 181 will run continuously tomaintain a supply of hydraulic fluid under elevated pressure for use insteering the vehicle 11. The length L effects movement of the double barlink means 139. The double bar link means 189 then moves, first, a firstmemher 191 inwardly or outwardly to correspondingly effect a fluid flowvia primary control valve 193 to the hydraulic ram power steering servos195 and 197. As the limit of travel of the first member 191 is reached,further movement of the double bar link :means 189 efiects movement ofthe second member 199 of the secondary control valve 201 for effecting amuch greater flow of hydraulic fluid to the hydraulic ram power steeringservos 195 and 197. The primary and secondary control valves 193 and 201are connected in parallel to supply hydraulic fluid under pressure tothe respective high pressure ends of the parallel connected hydraulicram power steering servos 195 and 197 for effecting the desired steer ofthe vehicle 11. Specifically, the primary and secondary control valveshave their discharge aperture connected in parallel with conduit 203 forrouting high pressure hydraulic fluid to the shaft end of the hydraulicram power steering servo 195 and to the piston end of hydraulic rampower steering servo 197 for effecting a steer to the left. Conversely,the primary and secondary control valves 193 and 201 have anotherdischarge aperture connected in parallel with conduit 205 for routinghigh pressure hydraulic fluid to the shaft end of hydraulic ram powersteering servo 197 and to the piston end of hydraulic ram power steeringservo 195 for effecting a steer to the right.

Separate and independently operable pumps 207 and 209 take suction froma reservoir 211 and supply high pressure hydraulic fluid to therespective primary control valve 193 and the secondary control valve201. Either, or preferably both, pumps may be operated continuously ifit is desired to have high pressure hydraulic fluid immediatelyavailable for the steering operation. On the other hand, either or bothof the first and second members 191 and 199 may have the sameconfiguration as the plunger 127 of FIG. 3 and employed with a switchsuch as switch 161 to start the respective pump when a demand for slowand fast power steering is made, as by movement of a respective memberin a predetermined direction. The pumps need not be operated in the samemanner. For example, it is possible to operate only the primary pump 207continuously and leave the secondary pump 209 idle until demand is madeupon the secondary control valve 201. That is, the second member E199will have a configuration and operative switch like plunger 127 of FIG.3 so as to start the secondary pump 209 only upon demand for high speedsteering.

In any event, the hydraulic fluid at elevated pressure is routed byeither the primary control valve 1193 alone or both the primary andsecondary control valves 193 and 201 to effect the desired rate ofsteering via the hydraulic power steering servos 195 and 197. As adegree of steer is effected, feedback from the steered section iseffected. Specifically, the hydraulic ram interconnection member 179 isdisplaced a distance D from the substantially vertical steering axis 23defined by the pivot connection, so that it returns the first and secondmembers 191 and 199 to the shut-off position to stop the flow ofhydraulic fluid at the moment the signalled degree of steer has beeneffected. The transistion to the shut-01f point is effected smoothly,since the second member 199 and the secondary control valve 201 arereturned to the shut-off position, first, to stop the large rate of flowof hydraulic fluid; and subsequently, the first member 191 and theprimary control valve 193 are returned to the shut-01f position to stopthe precisely controlled, low speed flow of hydraulic fluid to the powersteering servos 195 and 197.

As can be seen in FIG. 4, the reservoirs 185 and 21 1 are advantageouslypositioned close to their respective pumps '181, and 207 and 209.

FIG. 5 illustrates another embodiment of the invention in which thereservoir, as well as the control valve and pump, is emplaced closelyadjacent the hydraulic ram for which hydraulic power is to be supplied.Therein, the main beams 43 carrying the bucket 41 are cut away toillustrate more clearly the hydraulic rams 33 employed to raise andlower the bucket. The vehicle frame (not shown) of the vehicle carriesthe motor driven pump 57. The pump 57 has its suction side connectedwith reservoir 213 via conduit 214 and has its discharge side connectedwith main control valve 53 via conduit 216 The main control valve 53 hasone discharge aperture connected with the shaft end of the hydraulicrams 33 via conduit 215. The main control valve 53 has another dischargeaperture connected with the piston end of the hydraulic rams 33 viaconduit 217. The main control valve 53 has its return aperture connectedwith the reservoir 213 via conduit 219. The main control valve 53 may bepositioned hydraulically by a control valve, as illustrated in FIG. 2,or it may be positioned by a suitable lineal member from a controlconsole. Suitable lineal members comprise flexible members reciprocallyencased within an armored housing, or linear rods extending from acontrol lever. In any event, the main control valve 53 is suitablypositioned to direct the high pressure hydraulic fluid from pump 57 tothe piston end of the hydraulic rams 33 for raising the main beams 43;or to the shaft end of the hydraulic rams 33 for lowering the main beams43, as described hereinbefore. As illustrated, the pump, reservoir, andmain control valve are located closely adjacent to the hydraulic ramsthey power so as to keep the high pressure fluid lines short foreconomical initial installation, easy maintainence and less care inoperating the vehicle. The motor driving the pump may be controlled bymanual switches or by switches that are closed or opened in response tomovement of the control levers, or the like.

The operation of the system of FIG. 5 is the same as described withrespect to FIG. 2 hereinbefore.

FIG. 6 illustrates schematically the hydraulic rams 31 effecting tiltingof the bucket 41 via bell cranks 81, with the hydraulic pump andreservoir emplaced closely adjacent the hydraulic rams for which theysupply hydraulic fluid at elevated pressure. Specifically, the vehicleframe (not shown) carries the motor driven hydraulic pump 97. Pump 97has its suction side connected with the reservoir 221 via conduit 223.The pump 97 has its discharge side connected with the main control valvevia conduit 225. The main control valve 95 has one of its dischargeapertures connected with the shaft side of the hydraulic rams 31 viaconduit 227.. The main control valve 95 has its other discharge portconnected with the piston side of the hydraulic rams 31 via conduit 229.The main control valve 95 has its return port connected with reservoir221 via conduit 231. The main control valve 95 may be hydraulicallypositionable by a control valve such as control valve -109, FIG. 2, orit may be positionable by any one of the other conventional positioningmeans enumerated with respect to the main control valve 53, FIG. 5. Inany event, the main control valve 95 is operative todirect high pressurehydraulic fluid into either conduit 227 or 229 toeffect the desiredtilting of the bucket 41 via either retraction or extension of thehydraulic rams 31 and appropriate movement of the bell cranks 81 andlinks 89.

Operation of the hydraulic system of FIG. 6 is the same as describedhereinbefore with respect to the components of FIG. 2.

The materials of construction ordinarily employed with the type ofvehicle on which the systems are mounted will be employed in thisinvention.

This invention has been described with respect to having a single sumpwith which the respective pumps are connected via low pressure conduit;and the more advantageous structure in which separate reservoirs aredisposed closely adjacent the pumps which are, in turn, disposed closelyadjacent the respective hydraulically powered work performing means forwhich they supply hydraulic fluid at an elevated pressure.

Thus, it can be seen that the invention provides an improved vehiclehaving a plurality of discrete hydraulic systems that are separately andindependently operable to provide the following advantages:

(1) There are no long runs of high pressure tubing, high pressureconnections, and pivot connections to worry about in initialinstallation, in operation of the vehicle and in maintenance of thevehicle; consequently, there is less unsightly leakage;

(2) .By having separately controllable pumps, the vehicle can travelgreat distances without pumping large quantities of hydraulic fluid, aswas formerly required when a single pump, or multiple pumps, having thetotal capacity needed, was connected to the prime mover, or internalcombustion engine;

(3) By employing separate switch means, only the amount of oil that isnecessary to do the job being signaled is employed instead of pumpingenough to do a plurality of jobs; and

(4) In the event of failure of a hydraulic system, it is possible toturn off that particular hydraulic system and steer the vehicle back toa maintenance area to effect repairs in such a favorable environment,instead of having to shut down the vehicle and effect repairs in thefield before being able to drive it.

Although the invention has been described with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and the scope of theinvention.

What is claimed is:

1. In a vehicle having a plurality of work performing means that arepowered by hydraulic fluid, the improvement comprising;

a plurality of independently and separately actuatable hydraulic fluidpumps;

a plurality of independently and separately actuatable motors eachconnected with its respective one of said hydraulic fluid pumps;

a plurality of independently and separately actuatable switch means foractuating said motors and pumps; and

a plurality of independently and separately operable control meansconnected by conduit means with the discharge side of respective of saidpumps for controlling flow of fluid to and from said work performingmeans,

said control means including a control valve means having a plunger thatis moved inwardly and outwardly to effect direction and quantity of flowof fluid, said plunger having groove means with cntiguous cam means, arespective switch means being disposed adjacent said plunger, saidswitch means having actuation means by which said switch means isresponsively actuated into the on and off posi tions, said actuationmeans having roller means disposed in said groove means in the shut-offposition and adjacent said respective cam means contiguous with saidgroove means whereby said switch means is turned on upon movement ofsaid plunger in either direction to effect actuation of said motor andstart its associated pump supplying fluid to said control valve means.

2. The vehicle of claim 1 wherein said control means are operablyconnected with a lever means which also effects operation of arespective said switch means to both initiate pumping by a respectivepump and control the distribution of the pumped hydraulic fluid to therespective work performing means.

3. The vehicle of claim 1 wherein a respective manually operable switchmeans is provided for controlling said respective motor independently ofsaid respective control means.

4. The vehicle of claim 1 wherein said respective pumps and motors arepositioned on said vehicle adjacent said respective work performingmeans for keeping the high pressure hydraulic fluid flow conduit meansshort.

5. The vehicle of claim 4 wherein each said pump has its individualreservoir that is also positioned adjacent I said work performing means.

6. The vehicle of claim 1 wherein said control valve means includes acontrol valve and a main control valve; said control valve having saidplunger, and being connected with said main control valve such that saidmain control valve is positioned in response to the output of saidcontrol valve with which it is connected.

7. The vehicle of claim 1 wherein said switch means is employed tooperate a large current carrying contactor means intermediate a maingenerator and said motor, whereby said switch means and its associatedconductors can be relatively small.

8. A vehicle adapted to perform a plurality of work performing functionscomprising a frame, means for supporting said frame for movement,

5 means for driving said vehicle connected to said supporting means,

a plurality of work performing means on said frame adapted to behydraulically actuated, a plurality of hydraulic pumps,

motors,

each of said pumps being connected for actuation by its respective oneof said motors,

means connecting pumps to their respective work performing means tosupply hydraulic fluid to said work performing means,

a generator connected to and driven by said vehicle driving means,

switch means for connecting said generator to said motors whereby saiddriving means may be operated without the motor load on said generator,and

a plurality of control means connected to control the flow of hydraulicfluid from said motors to their respective work performing means. 9. Avehicle according to claim 8 including means responsive to said controlmeans for actuation of said switch means whereby when said control meansis actuated said switch means starts its associated motor and pumpresponsive to said control means actuation to supply fluid thereto.

10. A vehicle according to claim 8 wherein said vehicle is a front endloader having a bucket supported by arms, and

said work performing means includes actuators connected to said bucketand said arms to raise and lower and tilt said bucket.

11. The vehicle of claim 8 wherein said control means are operablyconnected with a lever means which also effects operation of arespective said switch means to both initiate pumping by a respectivepump and control the distribution of the pumped hydraulic fluid to therespective work performing means. 12. The vehicle of claim 8 whereinently of said respective control means. 13. The vehicle of claim 8wherein said respective pumps and motors are positioned on said vehicleadjacent said respective work performing means for keeping the highpressure hydraulic fiuid flow conduit means short. 14. The vehicle ofclaim 8 wherein each said pump has its individual reservoir that is alsopositioned adjacent said work performing means.

References Cited UNITED STATES PATENTS 65 EDGAR W. GEOGHEGAN, PrimaryExaminer U.S. Cl. X.R.

52 HE, DIGEST 2, 52 S a plurality of independent and separatelyactuatable a respective manually operable switch means is provided forcontrolling said respective motor independ-

